One such conventional technique is disclosed in Patent Document 1, where the product is referred to as an “electrically conductive member”.
The electrically conductive member disclosed in Patent Document 1 establishes electrical connection by a plurality of electrically conductive members making contact with each other, in which at least one of the electrically conductive members includes an electrically conductive hard carbon-containing film at a portion to be in contact with the other member. This electrically conductive member is used as contacts of keys.